Support ecdsa, ed25519, dsa temporary ssh key types

[mrdracon]

Description

Right now Yandex.Cloud packer plugin uses its own temporary ssh key generation step, but it does not have options for different ssh key types.
Packer builders now can use communicator.StepSSHKeyGen step from packer-plugin-sdk package, which have all the required options.

Use Case(s)

Fedora 33/34 builds, which do not accept ssh-rsa keys anymore

im currently working on PR